1. Field of the Invention
The present invention relates to a spray gun, and in particular to a spray gun which controls and sprays two fluids.
2. Description of the Prior Art
Spray guns which receive fluid under pressure and spray the fluid are used for a variety of purposes, including spraying water, paints, fertilizers, insecticides, herbicides and other fluids and are well known. Spray guns typically connect to a hose or other fluid line and have a handle or trigger which controls the flow. In addition, spray guns that spray two mixed fluids are known in the art.
However, these spray guns have several shortcomings which decrease their overall utility. Many spray guns are capable of spraying one fluid or a mixture, but are not able to change between spraying a single fluid and a mixture of fluids. In addition, such guns do not provide a stop for the trigger at the spraying position to make holding the gun during spraying more comfortable. The spray guns which do provide for mixing of more than one fluid have valving systems which may cause a burst of flow when the fluids are mixed and which do not control backflow when a single fluid is being sprayed. Furthermore, such devices do not provide for changing to spraying with a variety of hose or fluid line sizes adapted to interchangeable fittings. The hoses often require entrance of a first line at a first location on the gun and a second fluid line at a second remote location on the gun to accommodate the valve system, rather than a single simple attachment for both fluids.
An example of a spray gun is shown in U.S. Pat. No. 4,083,497. The spray gun includes a lever which pivots at its lower end in the handle portion of the gun and actuates a valve which extends up through the handle portion. A fitting at the rear of the gun accepts a single fluid line for spraying fluid through the barrel portion. The lever includes a lock at an upper end which engages the sliding upper finger receiving portion of the lever so that the lever does not need to be held in for continuous spraying. However, the '497 patent does not provide for selectively spraying a second fluid or provide for a fitting for a second fluid line. The lever cannot be changed from the position regulating a first fluid to regulating a first and second fluid.
It can be seen then, that a new improved spray gun is needed which provides for controlling flow of either one or two fluids. The gun should provide for spraying a single fluid, or by actuation of the lever, spraying a mixture of fluids. Such a gun should be able to control both fluids or a single fluid and provide for spraying with a catch position on the trigger so that the trigger is supported at a spraying position. Furthermore, such a spray gun should provide for adapting to various sizes of fluid lines and shapes of fluid lines or hoses entering the gun and provide interchangeable fittings for adapting to the fluid lines. Moreover, the valving should control and regulate pressure buildups in the hose leading to the spray gun and prevent backflow from one fluid into another. The present invention addresses these as well as other problems associated with spray guns.